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From: Stephen Leake <Stephen.Leake@gsfc.nasa.gov>
Subject: Re: win32ada design question/problem
Date: 1998/11/16
Message-ID: <ubtm7cxj0.fsf@gsfc.nasa.gov>#1/1
X-Deja-AN: 412471639
References: <364C5EDE.4F402D13@elca-matrix.ch>
 <72i3r9$o1r$1@nnrp1.dejanews.com>
Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA
Newsgroups: comp.lang.ada
Date: 1998-11-16T00:00:00+00:00
List-Id: <comp.lang.ada>

dennison@telepath.com writes:

> In article <364C5EDE.4F402D13@elca-matrix.ch>,
>   Mats.Weber@elca-matrix.ch wrote:
> > I just had a look at the win32ada binding and found that I could not use
> > it as I would like. Lets take this function as an example:
> >
> > >     function WriteFile(hFile                 : Win32.Winnt.HANDLE;
> > >                        lpBuffer              : Win32.LPCVOID;
> > >                        nNumberOfBytesToWrite : Win32.DWORD;
> > >                        lpNumberOfBytesWritten: Win32.LPDWORD;
> > >                        lpOverlapped          : Win32.Winbase.LPOVERLAPPED)
> > >                                                return Win32.BOOL;
> (snip)
> > Of course I can use 'Unchecked_Access to circumvent this, but then I
> > don't think that the binding is well designed if it requires
> > 'Unchecked_Access all over the place in code that uses it.
> 
> It wasn't designed at all. (by Ada folk, anway) Its a *thin* binding. If you
> want something that doesn't require unchecked programming to use, then you
> want a thick binding.

While I agree it wasn't well designed, I don't agree you need to go to
a thick binding. The binding should use 'out' parameter modes in the
places where C uses pointers to achieve output parameters. Most
compilers will map an 'out' parameter to a C pointer, since that's
what 'by reference' means.

-- Stephe